A friend had some EX1 mov files on his MBP, I copied and pasted them to my MBP and they played perfectly with QT. Then I copied and pasted them to my Dell PC. Now they don't play with QT (latest version), Vegas, or anything else on the PC. All that comes through is the audio.

I googled and couldn't come up with any thing solid. What's going on here?

This is why you keep the BPAV folders. When the files get converted for the Mac with Clipbrowser, they become incompatible with the PC. The reverse is also true. If you re-wrap for the PC, they don't work on a Mac.

So either you need to get back to the original BPAV folder, or you need to convert the files on the Mac to something your PC can read... like ProRes.